Attachment plug



Aug. 4, 1942. N. CHIRELSTEIN ATTACHMENT PLUG 2 Shets-s l Filed .J 1' 42Y TOR. 4 Nathan flumlsl'em, BY

Aug 4, 1942. N. CHIRELSTEIN ATTACHMENT PLUG Filed Jan. 1, 1942 2Sheets-Sheet 2 ATTOBNE'Y,

Patented Aug. 4, 1942 UNITED STATES PATENT OFFICE ATTACHMENT PLUG NathanChirelstein, Maplewood, N. J.

Application January 1, 1942, Serial No. 425,278

(Cl. 17336l) 7 Claims.

The invention here disclosed relates to electrical devices in the natureof attachment plugs.

Special objects of the invention are to effect the anchorage of thecontact blades in the cap and the connection of the conductor wires tothe blades, positively and securely and without injuring or breaking anyof the parts.

In previous constructions, the blades have been made of larger size thanthe openings intended to receive them and have been formed with barbedor toothed edges to form interlocking engagement with the cap material.Such constructions have been satisfactory where the cap is of rubber orlike material, which can expand under the drive of the barbed blades.However, for Bakelite and like hard and frangible materials, suchconstructions are not always satisfactory, because the oversize bladesstrain and crack or break the cap material. The materials like Bakelitealso are hard enough to bend back the barbs as they are driven andrender them more or less useless. And at best, these barbs will onlyhave a scraping effect on the Bakelite and will not actually have atruly anchored engagement in the cap.

The present invention aims to overcome all such objections and toprovide a construction particularly suitable for hard Bakelite caps, inwhich the blades and wires will be fully anchored and secured, withoutany tendencies toward injuring or weakening any of the parts.

According to this invention, the anchorage of the blades is accomplishedas a separate function. The blades are not oversize and do not have adriven fit in the cap. They simply have a mechanically proper easysliding fit and the anchorage is effected by separate devices, of amaterial and design especially selected for the purpose and arranged tomake positive interlocking engagement with the cap and with the blades.

The details of the invention and the novel features of construction bywhich all purposes of the invention are attained are set forth in thefollowing specification, illustrated in the accompanying drawings andbroadly covered in the claims.

The drawings show several different possible embodiments, but it will berealized, as the invention is appreciated, that structure may bemodifled and changed in various other ways, all within the true intentand broad scope of the invention as hereinafter defined and claimed.

Fig. 1 is a broken sectional view illustrating one practical embodimentof the invention, the

section being taken as on the plane of line I-I of Fig. 2.

Fig. 2 is a broken and partly sectional edge view of the plug.

Fig. 3 is a broken sectional detail similar to Fig. 1, but showing theblades, anchor clips and wires in process of being seated in the cap.

Fig. 4 is a view similar to Fig. 2, illustrating the assembly operationtaking place in Fig. 3.

Figs. 5 and 6 are broken sectional details, illustrating the assemblyand final positions of a modified form of the invention.

Figs. 7 and *8 are broken sectional details of other embodiments of theinvention.

Fig. 9 is an enlarged perspective View of one of the spring anchors usedin the Fig. 7 form of the invention.

Figs. 10 and 11 are broken sectional views of another embodiment of theinvention.

The cap body is represented at it), of more or less usual design havingcentral cord passage II, and narrow relatively deep blade receivingseats 12, at opposite sides of said passage.

The contact blades l3, are shown as notched at the inner ends of thesame at l4, for engagement over the wires l5, and as having outstruckwire contacting lugs [8, all substantially as illustrated in the earlierChirelstein Patent 2,181,576 of November 28, 1939. In that patenthowever, the blades are held in place primarily by the frictionalgripping effect of the rubber insulation of the wires compressiblygripped about the sides of the blades.

In the present invention, a separate definite anchor element, designedfor the special purpose, is provided for each blade.

In the first form of the invention illustrated, Figs. 1 to 4, the anchorelement consists of a narrow fiat strip ll, of resilient springmaterial, such as steel, doubled into substantially U-format-ion andhaving interlocking engagement both in the cap and with the blade.

In this particular illustration, the interlocking engagement with thecap is effected by cutting the ends of the U-shaped strip with sharplybevelled or angled ends i3, Fig. 4, which when the blade is fully seatedas in Fig. 2, are forced outwardly and positively bite into the endwalls of the blade cavity and the interlocking engagement with the bladeis effected by having the sides of the U-piece sharply angled inwardlyat is, to enter the notches or recesses 20, in the side edges of theblade.

As shown in Figs. 3 and l, the U-shaped spring anchor clip l1, is'of awidth to slide into the narrow blade openings I2, and may be set with agreater spread than the width of such openings, so as to engage the endwalls 2i, of the blade seats under tension, thereby to exert a constantspring gripping engagement in the cavity.

These anchor clips may be seated in the blade cavities prior to or atthe time of seating the blades and either prior to or after entering thewires, or assembling of all parts to be effected as part of one singleoperation.

Figs. 3 and 4 illustrate one method in which the anchor clips ll, arelocated in or over the blade seats, the wires positioned over the clipsand the blades then driven in, forcing ahead of them the wires and clipsto the fully seated and secured condition illustrated in Figs. 1 and 2.

The shanks of the blades need only have an easy sliding fit in the seatsand the anchor clips need only have a free sliding engagement. Henceonly very little force is necessary to assemble the parts. Onceassembled however, the parts to all practical eifects are permanentlysecured, because the anchor clips are positively interlocked to the capand positively interlocked to the blades as well.

The U-clips first shown have an upwardly bent middle portion 22, whichforces the wire sharply up into the notch in the lower end of the bladeshank, both to more firmly anchor the wire and assure good electricalengagement with the blade.

The inwardly convergent inclines 23, of the notches 20, tend to drivethe sharp edges ill, of the clips outward into more firmly interlockedengagement in the cap as the blades are forced to their seats and, tosimilar efiect, the reversely inclined shoulders 26, tend to force thesharp holding edges the more firmly outwardly in holding engagement withthe cap material, if the attempt is made to pull the blades out of theirseats. And when assembled, the expansive spring force of the clip servescontinuously and at all times to hold the parts snugly retained in theinterlocked relations described.

While flat strip stock may be generally preferred, the locking springmay be of round wire material, substantially as represented in Figs. 5and 6, where the same reference characters have been employed.

Fig, '7 illustrates a form of the invention in which the anchor clip issimply a flat bottom and straight sided U-shaped spring member havingoutwardly struck points 25, formed as by piercing the metal outwardly,to bite into the cap material and inwardly struck points or barbs 26, toengage in the edges of the blade shank. In this construction, the shankof the blade may have substantially straight sides, but the shankreduced in width as indicated at 21, to freely enter in between thesides of the anchorage clip.

Fig. 8 illustrates another embodiment, generally similar to that lastdescribed, but having an upward indentation 28, to engage over the wireend, this construction illustrating the arrangement in which it isintended to first locate the wire ends and to seat the clips in holdingengagement over such ends over the wires. In this form, the parts may beassembled, all as part of one operation, or the wires, be located, theclips then seated over the Wires and finally the blades driven into theanchor clips.

While it may be considered that the invention is particularly suited toBakelite and other frangible plug caps of a more or less brittle andnonyielding nature, it is realized that the invention is suited as wellto caps made of materials such as soft rubber, semi-hard rubber, hardrubber, fiber, porcelain, glass or other materials. The anchor elements,interposed between the side edges of the blades and the opposing wallsof the seat, to some extent, at least, take up the free space and beingof spring material, compensate for variations in size or inaccuracies inmanufacture, and also compensate to an extent for such changes as mightresult from sudden extremes in temperature or the like. The blades canbe of relatively soft metal, best suited to electrical conductingpurposes, since they perform no anchoring functions and th anchorelements, on the other hand, can be of hard spring steel, since theyneed serve only for anchorage purposes. The space occupied by theanchors in the blade seats reduces to that extent, the amount of themore expensive blade material required.

Instead of engaging the edges of the blades, the anchor clips may extendover a face or over opposite faces of the blades and engage with anopening or openings formed in the blades.

Thus as shown in Figs. 10 and 11, the anchors may be in the form ofrelatively fiat U-clips 3B, embracing opposite faces of the blades,having inwardly struck lugs 3!, to enter and interlock in openings 32,in th blades and having outwardly flared points 33, at the upper edgesinterlockingly engaged with the opposite faces of the blade cavities.The lower looped ends of these clips are shown as notched at 34, to passthe conductor Wires. These clips have enough inherent sprin tension totake up space in the oversize blade seats and thus firmly hold theblades locked in their seated relation in the plug cap.

What is claimed is:

1. An electric device in the nature of an attachment plug, comprising aninsulating body having a seat, a U-shaped spring clip having outturnedlocking edges at the free ends of the same for engagement with oppositewalls of said seat and inwardly directed bends below said outwardlyangled end portions, a contact blade disposed in said seat between theside arms of said spring clip and having recesses in opposite edgesreceiving said inwardly directed bends and a conductor wire in said seatand in engagement with said contact blade.

2. In an electrical device of the character disclosed, an insulatingbase having a cord passage and blade receiving openings at oppositesides of said cord passage, anchors of narrow, thin, fiat strip materialbent in U-forrnation seated in said blade receiving openings, contactblades having shank portions disposed within said U-shaped anchors, saidU-shaped anchors having outwardly struck portions interlocked with thewalls of the blade receiving openings and inwardly struck portionsinterlocked with. the shanks of the contact blades and wires extendingthrough said cord passage and electrically connected with the anchoredblades.

3. An attachment plug, comprising a cap of insulating material having acord passage theretions entered in said U-bent anchor wires and havingindentations in the side edges of the same, said wires having inwardlybent portions entered in said indentations and sharp-edged outwardlyangled ends interlocked with the'opposing walls of the blade seats andconductor wires extending through the cord passage and electricallyconnected with said contact blades.

4. An attachment plug, comprising a cap of insulating material having acord passage therethrough and blade seats at opposite sides of saidpassage, U-bent anchors of spring wire disposed in said seats, contactblades having shank portions entered in said U-bent anchor wires andhaving indentations in the side edges of the same, said wires havinginwardly bent portions entered in said indentations and sharp-edgedoutwardly angled ends interlocked with the opposing walls of the bladeseats and conductor wires extending through the cord passage andelectrically connected with said contact blades, the ends of said wiresbeing squeezed between the ends of the blade shanks and said anchorwires.

5. In an electrical device of the character disclosed, an insulatingbase having a cord passage and blade receiving openings at oppositesides of said cord passage, anchors of narrow, thin, flat strip materialbent in U-formation seated in said blade receiving openings, contactblades having shank portions disposed within said U- shaped anchors,said U-shaped anchors having outwardly struck portions interlocked withthe walls of the blade receiving openings and inwardly struck portionsinterlocked with the shanks of the contact blades, wires extendingthrough said cord passage and electrically connected with the anchoredblades, the ends of said Wires being caught between the ends of saidblades and said anchor strips.

6. In an electric device of the character disclosed, an insulating basehaving a cord passage and blade receiving openings at opposite sides ofsaid cord passage, flat contact blades in said openings and U-shapedanchors in said openings engaged over the ends of said blades andextending over opposite faces of the same, said U- shaped anchors havinginwardly struck lugs interlocked With the blades and having outwardlyflared ends interlocked with the walls of said blade receiving openings.

7. An attachment plug, comprising an insulating plug base having a cordpassage and blade receiving seats at opposite sides of said passage,U-shaped blade anchoring clips located in said seats, fiat contactblades driven into the bights of said U-shaped clips and having theopposite sides of said U-shaped clips embracing opposite sides of saidblades, said U-shaped clips having inwardly extending portionsinterlockingly engaged with the blades entered therein and outwardlyextending portions interlockingly engaged with the opposing walls of theseats in which said clips are located and wires in said cord passagehaving their ends secured in said seats by said U-shaped clips andentered blades.

NATHAN CHIRELSTEIN.

